The present invention relates to a processing apparatus equipped with a sealed vacuum device which contains a processing portion. In particular, it relates to a processing apparatus suitable for the manufacture of a semiconductor element, or the like. It also relates to a device manufacturing method which employs such a processing apparatus.
In the manufacture of a semiconductor element or the like, an exposing apparatus is used. As semiconductor elements have been rendered microscopic and highly integrated, X-ray has come to attract attention as one of the most promising choices of exposing light. The rate of the X-ray attenuation caused by the presence of the atmospheric air is extremely high. Therefore, when an X-ray is used as the exposure beam for a semiconductor exposing apparatus, the X-ray is guided into an exposure chamber through a beam duct which has been evacuated to an extremely high degree. In an exposure chamber, a substrate positioning stage and a mask holding apparatus are placed. A substrate positioning stage accurately positions a piece of substrate wafer or the like with the use of a chuck activated by suction. A mask holding apparatus holds a mask. In order to accurately expose the predetermined area of a piece of substrate by an exposure beam, the substrate piece must be very accurately positioned. Therefore, a laser interferometry based measuring device, or the like, is placed in an exposure chamber to measure the position of the substrate positioning stage in the chamber. In order to prevent X-ray attenuation, the atmospheric air in an exposure chamber is evacuated, creating a virtual vacuum chamber, while filling the evacuated exposure chamber with a small amount helium gas or the like to enhance the heat dissipation from the substrate in the wafer form, or a mask. Further, an exposure chamber is structured so that the pattern of the mask held by a mask holding apparatus is transferred onto the substrate by the X-ray as exposure light.
The internal pressure of an exposure chamber, or a vacuum chamber, affects the amount of X-ray transmission through the chamber. In other words, the change in the internal pressure of the vacuum chamber causes nonuniform exposure. The vacuum level falls as the atmospheric air, the gases from the bearings or the like, of the aforementioned positioning stage or the like, leak into the vacuum chamber, which in turn reduces the amount of the X-ray transmission through the internal space of the vacuum chamber. In other words, this kind of vacuum loss in an exposure chamber, or a vacuum chamber, is one of the main reasons why the performance of an exposing apparatus deteriorates in accuracy, and also why the throughput of an exposure apparatus reduces. Further, the internal temperature of a vacuum chamber locally increases due to the heat sources contained in the vacuum chamber, for example, the actuator or electrical wiring of the substrate positioning stage, the laser, or the like. Also, the internal temperature of the vacuum chamber is locally increased by the heat from the exposure light projected onto the substrate wafer and the mask. This kind of local temperature increase deforms the mask and the substrate, making it impossible to desirably transfer the mask pattern. In addition, the local temperature fluctuation creates a turbulence in the ambience gas in the measurement path of the laser beam projected by the laser interferometry based measuring device in the vacuum chamber, which results in fluctuation in the refractive index of this portion of the ambience gas. The fluctuation of the refractive index makes it impossible to accurately measure the position of the substrate positioning device with the use of a laser interferometry based measuring device. Thus, the pressure, temperature, and degree of purity of the gas in an exposure chamber, or a vacuum chamber, must be very precisely controlled as is evident from the above explanation.
Thus, the air in an exposure chamber, that is, a sealed container, is replaced with a small amount of inert gas such as pure helium, so that the internal space of the exposure chamber becomes a virtual vacuum space. Known as a method for keeping the gas in the exposure chamber pure while maintaining the internal space of the exposure chamber in the virtual vacuum state is the method disclosed in U.S. Pat. No. 5,267,292, which corresponds to EP application no. 363,168, for example. According to this patent, the internal pressure of the exposure chamber, or the sealed container, is kept constant by adjusting the flow rate at which the ambient gas in the exposure chamber is exhausted from the exposure chamber, and the flow rate at which very pure gas is allowed to flow into the exposure chamber, based on the internal pressure of the exposure chamber detected with the use of a pressure sensor. In this case, the flow rate at which the pure gas is allowed to flow into the exposure chamber is a certain number of times the flow rate at which unwanted gases flow into the exposure chamber.
Further, the following technology is disclosed in Japanese Laid-Open Patent Application No. 156625/1990. Thus, according to this patent, a sealed chamber is employed as an exposure chamber in which X-ray is used as exposure light. In operation, the atmospheric air in the sealed chamber is evacuated, and is replaced with a small amount of gas, for example, helium gas. As for the operational fluid for the static pressure bearings for the positioning stage in the evacuated sealed chamber (hereinafter, xe2x80x9cvacuum chamberxe2x80x9d), the ambient gas, that is, helium gas, in the vacuum chamber is used; the ambient gas is fed to the static pressure bearing after its pressure is increased with the use a compressor. The internal pressure of the vacuum chamber is controlled by adjusting the flow rate at which the helium gas, or the ambient gas, in the vacuum chamber is exhausted. More specifically, the internal pressure of the vacuum chamber is detected, and the flow rate at which the ambient gas in the vacuum chamber is exhausted by a vacuum pump is adjusted in response to the detected internal pressure of the vacuum chamber, so that the internal pressure of the vacuum chamber remains virtually constant. The helium gas suctioned out of the vacuum chamber by the vacuum pump is recirculated into the vacuum chamber to reduce helium gas consumption, while keeping constant the purity of the helium gas in the vacuum chamber so that exposure does not become uneven.
Japanese Laid-Open Patent Application No. 264404/1996 also discloses an ambient gas recirculating system. According to this patent, the ambient gas in a vacuum chamber is suctioned out by a vacuum pump, so that the internal pressure of the vacuum chamber remains constant at a predetermined level. The ambient gas suctioned out of the vacuum chamber is compressed by a compressor, and stored in a tank. Then, this ambient gas compressed and stored in the tank is recirculated into the vacuum chamber after being purified by a gas purifier, so that the rate at which ambient gas such as helium gas, which is rather expensive, is utilized, is improved, reducing thereby the cost for running the apparatus.
There is a technology for controlling the internal environment, of a semiconductor exposing apparatus, the ambient gas of which is the atmospheric air. According to this technology, the chamber in which an exposing apparatus is placed is connected to an air conditioning apparatus, which prevents the internal temperature of the chamber from being increased by the heat sources, for example, a mechanical power source such as a motor, electrical wiring, a laser, and the like, in the chamber, so that the internal temperature of the chamber remains constant at a predetermined level. This type of air conditioning apparatus is constituted of a fan, and a heat exchanger such as a heater or a cooler. It takes in the air from within a chamber or the atmospheric air, adjusts the temperature of the air by the heat exchanger, and sends the air into the chamber by the fan through the intake opening of the chamber. In other words, it controls the temperature of the ambient air in the chamber by circulating the air through a predetermined path, so that the temperature of the ambient air in the chamber does not fluctuate, and does not becomes uneven. Further, the dust in the air is removed by a filter disposed in the air circulation path so that the cleanliness of the chamber is controlled.
However, the above described exposure chamber based on the conventional technologies has a problem, even though it can reduce unevenness in temperature in the chamber by eliminating local temperature increase, and therefore, the ambient gas in the chamber is prevented from becoming turbulent. The problem is, if the fan of the air conditioner is disposed more than a certain distance away from the exposing portion, the velocity of the down flow created in the chamber does not reach a predetermined velocity, and therefore, the fan must be disposed immediately adjacent to the exposing portion. If the fan is placed immediately adjacent to the exposing portion, the vibration generated by the fan is transmitted through the plumbing or the like, causing the positioning stage or mask holding apparatus of the exposing portion to vibrate, even if the fan is not directly in contact with the exposing portion. The vibration of the stage or the like causes the positional relationship between a substrate and a mask to vary, making the line width of the pattern which will be formed on the substrate, different from the predetermined line width of a mask. Also, the vibration reduces resolution. Further, the driving portion of the fan generates a large amount of heat, and therefore, it must be cooled by providing it with the plumbing for water cooling. Provision of such plumbing, which requires a space for the plumbing, increases the size. or the foot print, of each exposing apparatus, reducing the number of exposing apparatuses which can be placed in each floor. This results in cost increase. In addition, if this type of air conditioning apparatus is disposed in a ambient vacuum, the lubricant in the rotational portions of the fan evaporates into the ambient vacuum, extremely reducing the durability of the fan. Thus, it is not desirable to place an air conditioning apparatus, which uses a fan, in a vacuum chamber in which there is an exposing apparatus, the exposing light of which is X-ray.
Technologies, such as the above described, for controlling the pressure, temperature, and purity of the ambient gas in a vacuum chamber which contains an exposing apparatus, to prevent the attenuation of X-ray, has been long known. However, those technologies suffer from problems. That is, they do not actively generate flows in the ambient gas in a vacuum chamber. Therefore, they fail to enhance the dissipation of the heat generated by the irradiation of the exposure light upon a substrate or a mask failing to prevent the temperature increase in the vacuum chamber. Also, they fail to sufficiently remove the heat generated by the other heat sources, for example, the driving means and electric wiring of the positioning stage, laser, and the like, in the vacuum chamber. Consequently, the temperature in the vacuum chamber locally increases or varies, which results in uneven exposure. In addition, the mask or the substrate is deformed by the heat generated by the exposure light. In other words, these technologies fail to achieve a high level of preciseness in pattern transferring.
Further, as described above, in order to precisely position a substrate, a laser interferometry based measuring device is used for measuring the position of the substrate positioning stage in the vacuum chamber in which an exposing apparatus is disposed. If a turbulence is generated in the. measurement path of the laser beam projected by the measuring apparatus, by the aforementioned heat, the reflective index of the ambient gas in the path varies, which causes measurement errors. This decreases preciseness in substrate positioning. Thus, the occurrence of turbulence in the ambient gas in the vacuum chamber, which adversely affects the accuracy of a laser interferometry based measuring device, must be prevented, so that the environment in the vacuum chamber remains stable.
Elaborating further on the reflective index of a laser beam in the atmospheric air in the normal stage; if the temperature changes 1xc2x0 C., the reflective index changes by approximately 1 ppm. This change in the reflective index causes an error in the measurement by a laser interferometry based measuring device. For example, if the true distance from the laser interferometry based measuring device to the stage is 500 mm, a temperature change of 1xc2x0 C. causes a measurement error of 500 nm, or 1 ppm of 500 mm. Since the accuracy in aligning a mask with a substrate is required to be no more than 10 nm, the accuracy of the interferometer for measuring the position of the stage must be no more than 5 nm. Thus, in order to reduce the measurement error of the interferometer, the temperature fluctuation in the measurement light path of the interferometer should be kept within approximately 0.01xc2x0 C. The reflective index fluctuation caused by temperature fluctuation in a helium filled chamber with an internal pressure of one fifth the atmospheric air pressure is approximately one fortieth the reflective index in an exposure chamber filled with an atmospheric air with the normal pressure. However, the temperature fluctuation should be kept within approximately 0.4xc2x0 C. Even under this kind of condition, in order to keep the measurement error of the interferometer below 2.5 nm to improve alignment accuracy, the temperature fluctuation must be kept within 0.2xc2x0 C. However, the vacuum chamber contains heat sources, that is, the driving means and wiring for the positioning stage, laser, and the like. They warm up the ambient gas adjacent to them, and the warmed ambient gas sometimes drifts into the measurement light path of the interferometer, causing the interferometer to be inaccurate.
A vacuum chamber, which contains a processing portion such as an exposing apparatus, also contains a substrate positioning stage for accurately positioning a substrate. The substrate positioning stage is provided with a suction chuck for holding a substrate. This type of chuck is connected to a vacuum pump, which is disposed outside the vacuum chamber, and is activated to maintain a certain amount of suction to keep a substrate held to the suction chuck of the substrate positioning stage. Thus, each time the vacuum pump is activated, a certain amount of the ambient gas in the vacuum chamber is exhausted through the suction chuck, and therefore, the internal pressure of the vacuum chamber temporarily decreases. In other words, exhausting the ambient gas in the vacuum chamber by the vacuum pump for the suction chuck occurs every time a substrate is held to the positioning stage by suction. In the case of a vacuum chamber based on the, prior technology, a certain amount of fresh ambient gas is added to the vacuum chamber. However, this supply of fresh ambient gas is for compensating for the leak of the atmospheric air into the vacuum chamber. In other words, it is not added in consideration of the loss of the ambient gas caused by the vacuum pump for the suction chuck. Therefore, if a processing apparatus is operated for a long period of time, the amount of the ambient gas in the vacuum chamber exhausted by the vacuum pump for the suction chuck becomes too large to be compensated for by the certain amount of fresh ambient gas added to the vacuum chamber to compensate for the aforementioned leak of the atmospheric air into the vacuum chamber. Consequently, the internal pressure of the vacuum chamber gradually decreases in spite of the addition of the aforementioned fresh supply of ambient gas; it is possible that the internal pressure of the vacuum chamber cannot be accurately controlled. If the internal pressure of the vacuum chamber cannot be accurately controlled, X-ray transmittance is adversely affected, resulting in uneven exposure. In other words, exposure accuracy deteriorates, which is one of the essential problems in the prior technologies.
Also in the cases of the above described prior technologies, the ambient gas in a vacuum chamber is suctioned out to maintain the internal pressure of the vacuum chamber at a predetermined vacuum level. Then, the ambient gas suctioned out of the vacuum chamber is purified, and recirculated into the vacuum chamber, improving the rate at which helium gas, that is, expensive ambient gas, is utilized during the operation of a processing apparatus. This reduces the consumption of the expensive ambient gas, reducing thereby the cost for running the apparatus. However, when it is necessary to stop the apparatus for the maintenance of a semiconductor exposing apparatus or the like disposed in the vacuum chamber, or at the end of an operation, first the ambient gas in the vacuum chamber is released into the atmosphere from the vacuum chamber or the ambient gas recirculating system. Next, the vacuum chamber is filled with nitrogen gas or air with the normal pressure. Then, the maintenance operation is carried out, or the apparatus is completely stopped. In other words, each time the apparatus is stopped for maintenance or the like, helium gas as the ambient gas for the vacuum chamber, which is rather expensive, is released into the atmosphere. Therefore, the prior technologies could not reduce helium gas consumption; they could not reduce the cost for running a processing apparatus.
The present invention is made in consideration of the above described problems which must be solved. The primary object of the present invention is to provide a processing apparatus, the internal ambience of which is stable. This is accomplished by creating a flow of the ambient gas in a predetermined direction in the sealed vacuum chamber of the processing apparatus to eliminate the unevenness in the internal temperature of the sealed vacuum chamber while preventing the ambient gas in the vacuum chamber from becoming turbulent.
Another object of the present invention is to provide a processing apparatus, the internal pressure of the sealed vacuum container of which is controlled with higher accuracy. This is accomplished by effectively compensating for the decrease in the internal pressure of the sealed vacuum chamber.
Another object of the present invention is to provide a processing apparatus which consumes a much smaller amount of ambient gas, and therefore, costs less to run, compared to conventional apparatus. This is accomplished by storing the ambience gas in its sealed vacuum container, in the ambient gas recirculating system before stopping the apparatus.
Another object of the present invention is to provide a device manufacturing method which employs a processing apparatus such as those described above.
A processing apparatus according to the present invention for accomplishing at least one of the above described objects is characterized in that it comprises:
a sealed vacuum chamber which contains a processing portion;
a pressure controlling system which keeps the internal pressure of the sealed vacuum chamber constant at a predetermined level by exhausting the ambient gas in the sealed vacuum chamber;
and an ambience gas recirculating system which recirculates the ambient gas exhausted from the sealed vacuum chamber back into the sealed vacuum chamber; and
wherein the ambience gas recirculated by the ambience gas recirculating system is blown into the sealed vacuum chamber so that a gas flow is generated in a predetermined direction along the aforementioned processing portion.
Regarding the above processing apparatus, it is desired that ambient gas in the sealed vacuum chamber is exhausted by a pump or a compressor;
the ambient gas recirculated by the ambient gas recirculating system is blown into the sealed vacuum chamber through an intake orifice disposed in the top portion of the sealed vacuum chamber, so that a downward gas flow is generated toward an exhaust orifice disposed in the bottom portion of the sealed vacuum chamber;
the ambient gas recirculated by the ambient gas recirculating system is blown into the sealed vacuum chamber, toward the light path of the laser interferometry based measuring device disposed in the sealed vacuum chamber;
a certain portion of the ambient gas recirculated by the ambient gas recirculating system is blown into the sealed vacuum chamber through the intake orifice disposed in the top portion of the sealed vacuum chamber, so that a downward gas flow is generated toward an exhaust orifice disposed in the bottom portion of the sealed vacuum chamber, while the rest of the gas recirculated by the gas recirculating system is blown into the vacuum chamber, toward the light path of the laser interferometry based measuring device disposed in the sealed vacuum chamber;
the ambient gas recirculating system is provided with a chemical filter, which is located where the ambient pressure is equal to, or greater than, the atmospheric air pressure:
the ambient gas recirculating system is provided with a temperature control portion for adjusting the temperature of the ambient gas;
a sensor for measuring the temperature of the ambience gas is disposed at the intake orifice, and the temperature control portion is controlled in response to the results of the measurement by the sensor;
a portion of the ambient gas recirculating system which exhausts the ambient gas in the sealed vacuum chamber is constituted of two ambient gas recirculating branches, and a valve for controlling the ambient gas flow rate is connected into the branch with the smaller flow rate;
the processing portion contained in the sealed vacuum chamber is an exposing apparatus for substrate exposure.
The second processing apparatus in accordance with the present invention for accomplishing one of the aforementioned objects is characterized in that it comprises:
a sealed vacuum chamber which contains a processing portion; and
an ambient gas recirculating system which exhausts the ambient gas in the sealed vacuum chamber, increases the pressure of the exhausted gas, and recirculates it into the vacuum chamber, with the use of a compressor or a pump;
wherein the ambient gas recirculated by the ambient gas recirculating system is blown into the sealed vacuum chamber so that a gas flow is generated in a predetermined direction, adjacent to the aforementioned processing portion.
Regarding the above processing apparatus, it is desired that the ambient gas recirculated by the ambience gas recirculating system is blow into the sealed vacuum chamber through an intake orifice disposed in the top portion of the sealed vacuum chamber, so that a downward gas flow is generated toward an exhaust orifice disposed in the bottom portion of the sealed vacuum chamber;
the ambient gas recirculated by the ambient gas recirculating system is blow into the sealed vacuum chamber, toward the light path of the laser interferometry based measuring device disposed in the sealed vacuum chamber;
a certain portion of the ambient gas recirculated by the ambience gas recirculating system is blown into the sealed vacuum chamber through the intake orifice disposed in the top portion of the sealed vacuum chamber, so that a downward gas flow is generated toward an exhaust orifice disposed in the bottom portion of the sealed vacuum chamber, while the rest of the gas recirculated by the gas recirculating system is blown into the vacuum chamber, toward the light path of the laser interferometry based measuring device disposed in the sealed vacuum chamber;
the ambient gas recirculating system is provided with a chemical filter, which is located where the ambient pressure is equal to, or greater than, the atmospheric air pressure;
the ambient gas recirculating system is provided with a temperature control portion for adjusting the temperature of the ambient gas;
a sensor for measuring the temperature of the ambient gas is disposed at the intake orifice, and the temperature control portion is controlled in response to the results of the measurement by the sensor;
a portion of the ambient gas recirculating system which exhausts the ambient gas in the sealed vacuum chamber is constituted of two ambience gas recirculating branches, and a valve for controlling the ambient gas flow rate is connected into the branch with the smaller flow rate;
the processing portion contained in the sealed vacuum chamber is an exposing apparatus for substrate exposure.
The third processing apparatus in accordance with the present invention for accomplishing one of the aforementioned object is characterized in that it comprises:
a sealed vacuum chamber which contains a processing portion;
a pressure controlling system which keeps the internal pressure of the sealed vacuum chamber constant at a predetermined level by exhausting the ambient gas in the sealed vacuum chamber;
an ambient gas recirculating system which increases the pressure of the ambient gas exhausted from the sealed vacuum chamber, and recirculates this exhausted ambient gas with the increased pressure into the sealed vacuum chamber; and
an ambient gas supplying device for adding ambient gas to the sealed vacuum chamber.
Regarding the above processing apparatus, it is desired that the pressure controlling system comprises:
a valve for controlling the flow rate of the ambience gas;
a pump or a compressor;
a pressure sensor for detecting the internal pressure of the vacuum chamber; and
a controller which controls the ambient gas flow rate control valve in response to the results of the measurement by the pressure sensor;
the ambient gas recirculating system comprises:
a tank for storing the ambience gas exhausted by the pump or compressor; and
a flow rate control portion or a regulator for recirculating the ambient gas stored in the tank, into the sealed vacuum chamber;
the ambient gas recirculating system is provided with a chemical filter, which is located where the ambient pressure is equal to, or greater than, the atmospheric air pressure;
the ambient gas recirculating system is provided with a temperature control portion for adjusting the temperature of the ambient gas;
a sensor for measuring the temperature of the ambience gas is disposed at the intake orifice, and the temperature control portion is controlled in response to the results of the measurement by the sensor;
a portion of the ambient gas recirculating system which exhausts the ambient gas in the sealed vacuum chamber is constituted of two ambient gas recirculating branches, and a valve for controlling the ambient gas flow rate is connected into the branch with the smaller flow rate;
the processing portion contained in the sealed vacuum chamber is an exposing apparatus for substrate exposure.
The fourth processing apparatus in accordance with the present invention for accomplishing one of the aforementioned object is characterized in that it comprises:
a sealed vacuum chamber which contains a processing portion;
a pressure controlling system which keeps the internal pressure of the sealed vacuum chamber constant at a predetermined level by exhausting the ambient gas in the sealed vacuum chamber; and
an ambient gas recirculating system which recirculates the ambient gas exhausted from the sealed vacuum chamber, back into the sealed vacuum chamber; and
a high pressure ambient gas recirculating system which increases the pressure of the ambient gas exhausted from the sealed vacuum chamber, and recirculates this ambient gas with the increased pressure into the sealed vacuum chamber.
Regarding the above apparatus, it is desired that the apparatus comprises:
an ambient gas supply system for adding ambient gas to the sealed vacuum chamber;
the pressure controlling system comprises:
a valve for controlling the flow rate of the ambient gas;
a pump or a compressor;
a pressure sensor for detecting the internal pressure of the vacuum chamber; and
a controller which controls the ambient gas flow rate control valve in response to the results of the measurement by the pressure sensor;
the ambient gas recirculating system comprises a tank for storing the ambient gas exhausted by the pump or compressor, and a flow rate control portion, and recirculates the ambient gas stored in the tank into the sealed vacuum chamber at a predetermined flow rate through the flow rate control portion; and
the high pressure ambient gas recirculating system comprises: a high pressure tank for storing the ambient gas exhausted by the pump or compressor and then highly compressed; and a regulator which recirculates the high pressure ambient gas to the sealed vacuum chamber while allowing the gas to decompress;
the ambient gas recirculating system comprises a control valve which controls the gas flow rate of the ambient gas recirculating system in response to the results of the measurement of a pressure sensor for measuring the internal pressure of the tank in the ambient gas recirculating system;
the control valve adds ambience gas to the tank, or suctions out the ambient gas in the tank;
a pump for activating a suction chuck contained in the sealed vacuum chamber is connected into the ambient gas recirculating system;
at least one of the ambient gas recirculating system or high pressure ambient gas recirculating system, or both, are provided with a chemical filter, which is located where the ambient pressure is equal to, or greater than, the atmospheric air pressure;
at least one of the ambient gas recirculating system or high pressure ambient gas recirculating system, or both, are provided with a temperature control portion for adjusting the temperature of the ambient gas;
a sensor for measuring the temperature of the ambience gas is disposed at the intake orifice, and the temperature control portion is controlled in response to the results of the measurement by the sensor;
a portion of the ambient gas recirculating system which exhausts the ambient gas in the sealed vacuum chamber is constituted of two ambient gas recirculating branches, and a valve for controlling the ambient gas flow rate is connected into the branch with the smaller flow rate;
the processing portion contained in the sealed vacuum chamber is an exposing apparatus for substrate exposure.
The fifth processing apparatus in accordance with the present invention for accomplishing one of the aforementioned objects is characterized in that it comprises:
a sealed vacuum chamber which contains a processing portion;
a pressure controlling system which keeps the internal pressure of the sealed vacuum chamber constant at a predetermined level by exhausting the ambient gas in the sealed vacuum chamber;
an ambient gas recirculating system which recirculates the ambient gas exhausted from the sealed vacuum chamber back into the sealed vacuum chamber; and
a high pressure ambience gas recirculating system which increases the ambient gas exhausted from the sealed vacuum chamber, and recirculates this ambient gas with the high pressure into the sealed vacuum chamber;
wherein before the processing apparatus is stopped, at least a portion of the ambience gas is stored in at least one of the ambient gas recirculating system or high pressure ambient gas recirculating system, or both.
Regarding the above processing apparatus, it is desired that the apparatus also comprises:
an ambient gas supplying system for adding ambient gas to the sealed vacuum chamber;
the pressure controlling system comprises:
a valve for controlling the flow rate of the ambience gas;
a pump or a compressor;
a pressure sensor for detecting the internal pressure of the vacuum chamber; and
a controller which controls the ambient gas flow rate control valve in response to the results of the measurement by the pressure sensor;
the ambient gas recirculating system comprises a tank for storing the ambience gas exhausted by the pump or compressor, and a flow rate control portion, and recirculates the ambient gas stored in the tank into the sealed vacuum chamber at a predetermined flow rate through the flow rate control portion; and
the high pressure ambient gas recirculating system comprises: a high pressure tank for storing the ambient gas exhausted by the pump or compressor and then highly compressed; and a regulator which recirculates the high pressure ambient gas to the sealed vacuum chamber while allowing the gas to decompress;
a valve is placed on both the upstream and downstream sides of at least one of the tank and high pressure tank;
when the processing apparatus is stopped; the valve on the downstream side of the tank is closed, the ambient gas is sent into the tank by activating the pump or compressor; and then, the valve on the upstream side of the tank is closed to keep the ambience gas stored in the tank;
at least one of the ambient gas recirculating system and high pressure ambient gas recirculating system is provided with a bypass to the sealed vacuum chamber;
wherein the processing apparatus is stopped, the recirculating system is opened to the bypass, and the ambient gas is stored in the recirculating system and bypass;
at least one of the ambient gas recirculating system and high pressure ambience gas recirculating system is provided with a chemical filter, which is located where the ambient pressure is equal to, or greater than, the atmospheric air pressure;
at least one of the ambient gas recirculating system and high pressure ambient gas recirculating system is provided with a temperature control portion for adjusting the temperature of the ambient gas;
a sensor for measuring the temperature of the ambient gas is disposed at the intake orifice, and the temperature control portion is controlled in response to the results of the measurement by the sensor;
a portion of the ambient gas recirculating system which exhausts the ambient gas in the sealed vacuum chamber is constituted of two ambient gas recirculating branches, and a valve for controlling the ambient gas flow rate is connected into the branch with the smaller flow rate;
the processing portion contained in the sealed vacuum chamber is an exposing apparatus for substrate exposure.
The sixth processing apparatus in accordance with the present invention for accomplishing one of the aforementioned object is characterized in that it comprises:
a sealed vacuum chamber which contains a processing portion;
an ambient gas recirculating system which exhausts the ambient gas in the sealed vacuum chamber, increases the pressure of the exhausted ambient gas, and recirculates the exhausted ambient gas with the higher pressure back into the sealed vacuum chamber, with the use of a compressor or a pump;
wherein the ambient gas recirculated by the recirculating system is blown into the sealed, vacuum chamber so that a gas flow is generated in a predetermined direction, adjacent to the measuring portion.
Regarding the above processing apparatus, it is desired that the recirculating system is provided with a chemical filter, which is located where the ambient pressure is equal to, or greater than, the atmospheric air pressure.
Further, according to another aspect of the present invention for accomplishing one of the aforementioned object, a device manufacturing method, a device manufacturing method is characterized in that it employs the above described first, second, third, fourth, fifth or sixth processing apparatus in accordance with the present invention.
According to the primary aspect of the present invention, a processing apparatus comprises: a sealed vacuum chamber which contains a processing portion; a pressure controlling system which keeps the internal pressure of the sealed vacuum chamber constant at a predetermined level by exhausting the ambient gas in the sealed vacuum chamber; and an ambient gas recirculating system which recirculates the ambient gas exhausted from the sealed vacuum chamber back into the sealed vacuum chamber; wherein the ambient gas recirculated by the ambient gas recirculating system is blown into the sealed vacuum chamber so that a gas flow is generated in a predetermined direction along the aforementioned processing portion. Therefore, the heat or the like generated by the heat sources in the sealed vacuum chamber is sufficiently removed by heat dissipation, preventing the internal temperature of the sealed vacuum chamber from becoming locally uneven. Thus, the ambient gas in the sealed vacuum chamber is prevented from becoming turbulent. Consequently, the ambient gas in the sealed vacuum chamber remains stable.
Further, with the use of a vacuum pump as the means for driving the ambient gas in the ambient gas recirculating system, vibration such as the one caused by the blower of a conventional air conditioner does not occur, reducing the overall amount of the vibration, improving therefore the apparatus in terms of resolution. Further, the employment of a vacuum pump saves space, which reduces the apparatus cost. Also, providing the ambient gas recirculating system in a processing apparatus with ordinary filters or chemical filters makes it possible to efficiently remove the particles in the ambient gas, or substances produced through chemical reaction triggered among the elements in the ambient gas by exposure light. Therefore, exposure energy is prevented from attenuating, preventing thereby the throughput of the apparatus from reducing, as well as preventing uneven exposure.
Therefore, application of the present invention to a semiconductor exposing apparatus makes it possible to more precisely control the pressure of the ambient gas in a vacuum chamber as an exposing chamber, preventing exposing light such as X-ray from attenuating, preventing uneven exposure, preventing a mask or a substrate from being inaccurately positioned due to heat, reducing the possibility of measurement error, and improving positioning accuracy and alignment accuracy. Therefore, highly accurate exposure is possible. In addition, application of the present invention to a measuring apparatus makes it possible to very accurately measure an object, that is, without the possibility of measurement error.
Further, according to another aspect of the present invention, a processing apparatus comprises: a sealed vacuum chamber which contains a processing portion; a pressure controlling system which keeps the internal pressure of the sealed vacuum chamber constant at a predetermined level by exhausting the ambient gas in the sealed vacuum chamber; and an ambient gas recirculating system which recirculates the ambient gas exhausted from the sealed vacuum chamber, back into the sealed vacuum chamber; and a high pressure ambient gas recirculating system which increases the pressure of the ambient gas exhausted from the sealed vacuum chamber, and recirculates this ambient gas with the increased pressure into the sealed vacuum chamber. In this processing apparatus, an additional supply of fresh ambient gas is added to the ambient gas recirculating system from an ambient gas supply source other than the ambient gas supply source, vacuum pump for operating a suction chuck, high pressure tank connected to the high pressure ambient gas recirculating system, and the like, which belong to the aforementioned ambient gas recirculating system. Therefore, the pressure decrease which occurs in the sealed vacuum chamber and the ambient gas recirculating system as the ambient gas is exhausted by the vacuum pump for holding a substrate by suction is effectively compensate for. Thus, the internal pressure of the sealed vacuum chamber is controlled with improved accuracy.
Further, according to another aspect of the present invention, a processing apparatus comprises: a sealed vacuum chamber which contains a processing portion; a pressure controlling system which keeps the internal pressure of the sealed vacuum chamber constant at a predetermined level by exhausting the ambient gas in the sealed vacuum chamber; and an ambience gas recirculating system which recirculates the ambient gas exhausted from the sealed vacuum chamber, back into the sealed vacuum chamber; and a high pressure ambient gas recirculating system which increases the pressure of the ambient gas exhausted from the sealed vacuum chamber, and recirculates this ambient gas with the increased pressure into the sealed vacuum chamber. In this processing apparatus, when the apparatus is stopped for maintenance or the like, at least a certain portion of the ambient gas is stored in the ambient gas recirculating system and/or the high pressure ambient gas recirculating system, in particular, in the high pressure tanks of the recirculating systems. In other words, the ambient gas is not entirely discharged into the atmospheric air. With this arrangement, the consumption of the ambient gas, that is, helium gas or the like, which is rather expensive, is greatly reduced, making it possible to greatly reduce the cost for running the apparatus.
Further, according to another aspect of the present invention, a processing apparatus comprises: a sealed vacuum chamber which contains a processing portion: and an ambient gas recirculating system which exhausts the ambient gas in the sealed vacuum chamber, increases the pressure of the exhausted gas, and recirculates it into the vacuum chamber, with the higher pressure back into the sealed vacuum chamber, with the use of a compressor or a pump. In this apparatus, a means for measuring the distances among the components in the sealed vacuum chambers, and the amounts of their shifts, is disposed in the sealed vacuum chamber. In operation, the ambient gas recirculated by said ambience gas recirculating system is blown into said sealed vacuum chamber so that a gas flow is generated in a predetermined direction along the aforementioned processing portion, preventing the internal temperature of the sealed vacuum chamber from locally becoming uneven, preventing thereby the ambient gas becoming locally turbulent. Therefore, the ambient gas in the sealed vacuum chamber remains stable, eliminating the possibility of measurement error of the measuring means. This apparatus further comprises a chemical filter, which is connected into the ambient gas recirculating system, at a point where the pressure of the ambient gas is higher compared to the other portions of the ambient gas recirculating system. Therefore, it is possible to effectively remove the particles in the ambient gas, and the substances produced in the ambient gas through the chemical reactions among the elements in the ambient gas.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.